Device for controlling precessional forces in gyroscopes



y A. KRUSSMANN 2,349,287

DEVICE FOR CONTROLLING PRECESSIONAL FORCES IN GYROSCOPES Filed March '1,1940 //7/ en for: 56' A AUJJMANN,

H/s Arraewrx DEVICE FOR CONTROLLING PRECESSEUNAE.

, FORCES n1 GOSCQPES Adolf Kriissmann, lBerlin-Wilmersdori, Germany;vested in the Alien Property Custodian AppiicationMarch l, litw, SerialNo. senses In Germany February ill, 1939 41 Claims, (@i. 57)

The invention relates to improvements in devices for controllingprecessional forces in gyroscopes. device for controlling precesslonalforces in which the precesslonal force is counterbalanced by anauxiliary force controlled by that precessional force, said force beingfor instance an electrically controlled force;

Arrangements hitherto known have only been adapted to compensate forunidirectional precessional forces. In order to make such arrangementsresponsive to forces opposed in direction, a spring force was applied tothe gimbal ring of the gyroscope causing a deflection of the gimbalring, the deflecting tendency being countel-acted by some forcecontrolled by the deflection of the gimbal ring so that even in theabsence of any precessional force an auxiliary force of a predeterminedamount was necessary for balancing the tension of the spring. The use ofsuch springs, however, has the following disadvantages: The measurementis dependent on the temperature as the spring tension varies under theinfluence of the temperature, of the aging oi the spring and of theauxiliary force in as much as-if the precessional force remainsconstant-fluctuations in the latter alfect the.

The invention refers particularly to a y ture s oscillates between thecontacts 6, l with out touching same.

The two contacts t, l are connected via resistors Ml, is, respectively,to the ends of a potentiometer resistance It fed by a direct currentsource B and having a center tap It, a D. C. re-

sponsive indicating instrument is of the moving coll type and a movablecoreless coil is being connected in series between said center tap itand said armature s. The coil 2% is secured to the other arm, 29 of thegimbal ring l and is substantially rectllinearly movable in the magneticfield of the permanent magnet 22, thus forming a counterbalancingsystem. The gimbal ring is supported so as not to be subject to anyforce in the absence of the precessional force and the auxiliaryforce-the latter being in this embodiment the electric power source B,

amount of the deflection of the gimbal ring necessary to producethebalancing force 50 that the spring characteristic influences themeasuring perpendicular to the axis 3 of the gimbal ring.

Said gimbal ring represents a two-armed lever, one arm 4 of whichcarries an insulating piece 5 to which are secured two leaf springcontacts 6 and l. A polarized relay is provided having twopermanentmagnets NS and NS' connected by a soft-iron core 0 and having a softiron armature 0 whcih is turnably mounted with its one endon the middleportion of the soft iron core 8 thereby polarizing the free end of thearmature 9,

said armature-carrying at its free end two contactslll, ll. 'Iwo coilsl2, I3 mounted on the so that the movement of the gimbel ring remainsunaffected by any resetting force.

Be it assumed that the gimbal ring 6 is turned about the axis w-b lyingin two vertical planes, one passing through the axis 3, the otherpassing through the axis H, the gimbal ring is deflected about its axis3 as indicated by the arrows c or d. Thus, the contact 8 of the lever 45touches periodically the contact ill of the arms .ture-Q, or contact 8of the lever periodically touches contact ll of said armature,.thefrequency of the contact closing corresponding to the alternatingcurrent frequency of they net? work RS. Thereby the following circuit'isperiodically. closed: Center tap it, movable coil 23 of the indicatinginstrument l9, coil 20 of the counterbalancing system, armature 9,contact It! or II, respectively, contact 8 or 1, respectively,

I! depends on the'duration of the contact be-' tween the armature 9 andthe contacts 6 or I, re spectively, and said duration in turn depends onthe contact pressure which increases in proportion to the gimbal ringdeflection. Hence, the

two legs of the core 8 are series connected to the alternating networkRS in sucha manner that, if the polarized relay is excited byalternoting current from the network RS, the armamean value of thiscurrent is an exact equivalent of the amount of the precessional forceand therefore of the rate of the turning about the axis ab. In this way,the precessional movement is counterbalanced by the electrodynamiccounteriorce of the system 20, 22, and the indicating instrument I9, 23furnishes an indication of the rate of turn in that its position isdependcut on or a measure of the precessional force exerted by thegyroscope. In order to avoid hunting of the device, dampening means areprovided comprising a fluid-filled vessel 24 and a piston 25 movabletherein and fastened to the free end of the gimbal arm 2!.

'delivered by coil 32.

If no A. C. is available for exciting the polarized relay, such currentmay be dispensed with. If precessional forces are present, the systembegins to swing automatically, thereby establishing the necessarycontact. In such cases, the frequency of oscillation increases accordingto the amount of the precession moment to be balanced. In order to avoidmechanical reaction on the gimbal ring in consequence of the closing ofthe contacts, the armature 9 or the contacts 6, I are resilientlymounted. In the case of equal contact pressures, the contacts supportedby rubber contact carriers allow manifoldly greater currents to passthan metallic contact springs while in addition the current flows moreevenly. To avoid shocks, stops 26 and 21 having rubber pads are providedfor limiting the movement of the armature of the polarized relay. Inthis way, sinusoidal armature oscillations are obtained -instead ofrectangular oscillations resulting in an even current flow in the coil20 and the indicating instrument l9.

According to Fig. 2, two toothed segments 30, 3| are arrangedsymmetrically relative to the gimbal axis 3 and rigidly coupled with thegimbal ring I of the gyroscopic turning indicator. One of said segments3! drives a gear wheel 33 mounturing instrument, for instance, a secondFerra motor 39 having a drum armature 42 and exciting coils 40, 4|, coil40 and coil 31 being fed in series from the network RS, coil 4| and coil38, on the other hand, being fed in series by the voltage The drumarmature 42 carries a gear wheel 43 meshing with the toothed segment 44rotatably mounted about an axle 44. The springs 46, 41 exert a certainreactionary force on the segment 44 and, hence, on the-drum 42. Thedirection responsive deflections of the second Ferraris motor are adirect equivalent of the amount and the direction of the precessionalforce to be measured. The toothed segment 44 may carry a jet pipe 48,this being part of a jet pipe relay known per se supplying amplified.fluid pressure impulses for actuation of a pressure means servo-motor 55for the adjustment of a controlled member, for instance, an aircraftrudder 56, in response'to the angular-velocity influencing thegyroscope.

ed on an axle 50 around which a coil 32 is rotat- SI of a two-phaseinduction or Ferraris motor 36' possessing a .drum 52 driving the gearwheel 33 and has exciting coils 31, 33 the axes of which areperpendicular to each other, coil 31 being fed by the alternatingnetwork RS while the other coil, 38, is fed by the alternatingelectromotive force induced in coil 32. A capacity 80 is provided forproducing the necessary phase angle of the.exciting currents in bothexciting coils 31, 38. Also, in this case, the gyroscope is mounted soas not to be acted upon by reactionary forces, i. e., in the absenceofprecessional and auxiliary forces, the gimbal ring may be turned aboutits axis 3 without hindrance by any resetting force. In the normalposition, the winding axis 53 of the coil 321s perpendicular to the axisof the magnetic induction field 34 so that novoltage is induced in thecoil and the Ferraris motor 33 is at a standstill. If, however, aprecessional moment acts on the gimbal ring, the coil 32 will be rotatedso that an alternating electromotive force is induced in said coil, thephase thereof. being reversed when the direction ofthe precessionalforce is reversed. As the winding 33 of the Ferraris motor isfed by thiselectromotive force, the Ferraris motor starts torun and turns back thetoothed segment and the gimbal ring I. In this way, an equilibrium isestablished between the precessional moment and the moment of theFerraris motor. Therefore, the value of the voltage lnduced in thebalanced condition is exactly proportional to the value of theprecessional force and, hence, to the angular velocity. This voltage ismeasured in a direction responsive meas- I claim:

l. A device for opposing and counterbalancing precession of anangular'rate gyroscope mounted for precessional movement comprising thecombination of an electric relay system including an A. C. power source,an electromagnet energized by said A. C. source to produce analternating magnetic field, a rotatable coil situated in the held of theelectromagnet, means associating said coil and the gyroscope so that thecoil is displaced relative to the electromagnetic field in proportion tothe degree of precessional movement of the gyroscope and in a directiondepending upon the direction of such precessional movement, to therebyprovide an induced variable alternating electromotive force in saidrelay system, a servo motor in said system controlled by the inducedelectromotive force from the rotatable coil and by the alternatingcurrent delivered thereto by the alternating power source, said servomotor being rotatably connected to the gyroscope to thereby exert anoppositely directed torque about the axis of precession of saidgyroscope counterbalancirig the precession thereof.

2. A device as claimed in claim 1 in which the servo motor is of theinduction type havingtwo V perpendicularly disposed field windings, oneofinduction motor, having similarly disposed and controlled fieldwindings in said relay system,

whose movement-is proportionalto the degree of precessional movement ofthe gyroscope.

4. A device for opposing and counterbalancing precession of an angularrate gyroscope mounted for precessional movement comprising thecomblnation of an A. C. supplied circuit having a relay whose voltageoutput is proportional to the degree of precessional movement of saidgyroscope, and a servo motor in said circuit, controlled by theoutput-of said relay and connected to said gyroscope to provide anopposing torque about the axis of precession of the gyroscope whichcounterbalances the precession of said gyroscope.

' 'ADOLF KR'USSMANN.

